Profile

Cover photo
Qiaochu Yuan
Worked at Machine Intelligence Research Institute
Attends University of California, Berkeley
Lives in Berkeley, CA
2,313 followers|160,578 views
AboutPosts

Stream

Qiaochu Yuan

Shared publicly  - 
 
I was staring at a bonfire on a beach the other day and realized that I didn’t understand anything about fire and how it works. (For example: what determines its color?) So I looked up some s…
6
Urs Schreiber's profile photoIgor Khavkine's profile photo
2 comments
 
There was a whole thing a few years ago about explaining this to 11-year olds. :-)
http://www.centerforcommunicatingscience.org/what-is-a-flame/
Add a comment...

Qiaochu Yuan

Shared publicly  - 
 
Ramanujan stuff.
I went to see The Man Who Knew Infinity yesterday. I have nothing much to say about the movie as a movie that wasn’t already said in Scott Aaronson’s review, except that I learned a few…
13
4
Kram Einsnulldreizwei's profile photoQiaochu Yuan's profile photoJohn Baez's profile photo
4 comments
 
The closest cinema where it's playing seems to be a 1-hour drive away, south of Los Angeles near the coast.  And I bet that's under optimistic assumptions about traffic.  So it's about time and general hassle.
Add a comment...

Qiaochu Yuan

Shared publicly  - 
 
Previously we suggested that if we think of commutative algebras as secretly being functions on some sort of spaces, we should correspondingly think of cocommutative coalgebras as secretly being di…
3
Add a comment...

Qiaochu Yuan

Shared publicly  - 
 
Here's a fun question: is the empty function (from the empty set to itself) constant? Is it locally constant? 
3
1
John Baez's profile photoDavid Roberts's profile photoConrad Meyer's profile photoAllen Knutson's profile photo
15 comments
 
Presumably a constant function f:X->Y should factor through pt->Y uniquely. If that's the only definition, and X is empty, then "f is constant" iff |Y| = 1. Which is pretty weird!
Add a comment...

Qiaochu Yuan

Shared publicly  - 
 
It's common to think of monads as generalized algebraic theories; the most familiar examples, such as the monads on $latex \text{Set}$ encoding groups, rings, and so forth, have this flavor. Howeve...
4
1
Add a comment...

Qiaochu Yuan

Shared publicly  - 
 
In the previous post we described a fairly straightforward argument, using generating functions and the saddle-point bound, for giving an upper bound $latex \displaystyle p(n) \le \exp \left( \pi \…
4
2
Add a comment...

Qiaochu Yuan

Shared publicly  - 
 
More Ramanujan stuff.
(Part I of this post is here) Let $latex p(n)$ denote the partition function, which describes the number of ways to write $latex n$ as a sum of positive integers, ignoring order. In 1918 Hardy and …
13
2
iddrisu hanan's profile photo
 
Hello 
Add a comment...

Qiaochu Yuan

Shared publicly  - 
 
Let $latex k$ be a commutative ring and let $latex A$ be a $latex k$-algebra. In this post we’ll investigate a condition on $latex A$ which generalizes the condition that $latex A$ is a finit…
4
Add a comment...

Qiaochu Yuan

Shared publicly  - 
 
Mathematicians are very fond of thinking about algebras. In particular, it’s common to think of commutative algebras as consisting of functions of some sort on spaces of some sort. Less commo…
6
1
Add a comment...

Qiaochu Yuan

Shared publicly  - 
 
Very nice visualization of prime factorizations. 
10
4
Radu Grigore's profile photo
 
iirc, this is included in http://incrediblenumbersapp.com/, which is a nice app for kids
Add a comment...

Qiaochu Yuan

Shared publicly  - 
 
Here's a dumb riddle. We all know that a meromorphic function on a Riemann surface is a function to CP^1. We also all know that meromorphic functions on a Riemann surface form a field, and in particular a ring. So... why isn't CP^1 a ring object in the category of Riemann surfaces?

(It took me an embarrassingly long time to figure this out.)
1
Allen Knutson's profile photoJohn Baez's profile photoQiaochu Yuan's profile photoLuke Sciarappa's profile photo
7 comments
 
Is it because the point is not a Riemann surface?
Add a comment...
People
Have them in circles
2,313 people
Ashu Singhal's profile photo
Shiplu Ahmed's profile photo
Doug Cutrell's profile photo
qutbah selangor's profile photo
Anh Chau's profile photo
George Li's profile photo
Willie Wong's profile photo
Jitander Dudee's profile photo
Albertas Dvirnas's profile photo
Work
Occupation
Graduate Student
Employment
  • Machine Intelligence Research Institute
    Visiting Fellow, 2013 - 2013
  • PROMYS
    Counselor, 2012 - 2012
  • Stack Overflow, Inc.
    Intern, 2011 - 2011
Places
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Currently
Berkeley, CA
Previously
Boston, MA - New York, NY - Bellevue, WA - Nanjing, China - Singapore - Vancouver, WA - Cambridge, UK
Story
Introduction
I'm a third-year graduate student in mathematics at UC Berkeley. 
Bragging rights
USA Mathematical Olympiad Honorable Mention (2006), Siemens-Westinghouse Science and Technology Competition Semifinalist (2007), Intel Science Talent Search Finalist (2008), William Lowell Putnam Mathematical Competition Honorable Mention (2009), NSF Fellow (2012)
Education
  • University of California, Berkeley
    Mathematics, 2012 - present
  • Massachusetts Institute of Technology
    Mathematics, 2008 - 2012
  • University of Cambridge
    Mathematics, 2010 - 2011